I think there is something that is supposed to clamp onto the line that runs between the two swivel blocks, in order to shorten the "travel" of the boom, to bring it in closer while sailing upwind.

That rig in the picture above is a 3:1 ratio.

I have been toying with the idea of taking a traveler from a larger boat (24 ft) and installing it across the beam between the seats, and adding a fiddle block with cam and becket. That would eliminate the runs on the stern and make it easier to control a motor or make room for other things like lights and such.

With that setup, it would be a 4:1 ratio (2 pulleys in the fiddle w/cam and 2 more in a fiddle block on the boom). This would of course bring the traveler control, the main sheets and jib sheets all within a couple of feet...making it easier for single handed sailing.

That's the way I sailed the other day (fig.1). I'm thinking of putting another block on the end of the boom so the line doesn't run along the stern and would give a 4:1 and be out of the way more. What size mainsheet are you using? My blocks are less that 1". I used 5/16 line but I think I will try 1/4" the 5/16" didn't feed through the blocks that well. I'm in Florida so sailing is a year round thing here.

After rigging mine up and sailing I used 1/4 on the halyards (both main and jib) and jib sheets, and used 5/16 on the mainsheet. The mainsheet wound up being 42' long. (That's with the main touching the stays for downwind runs.)

You may want to add a few feet to that if you add another pulley block to the boom (I assume you would run up to the boom instead of across the stern).

I will set up mine and take some pic's. Give me a day or so because it's been raining here a lot. DaveD you are right about the line running to the boom and not across the back. I have an extra block or I'll use a double block and set it up that way also. My Venture has a similar setup but doesn't run along the boom the control line is at the stern.